JP5519796B2 - Precoding processing method and apparatus - Google Patents

Description

  The present invention relates to a communication technology field, and more particularly to a precoding processing method and apparatus.

  In a wireless communication system, in order to increase the data transmission rate and system throughput, the multi-input and multi-output (MIMO) technology is used to obtain the maximum data transmission throughput of the system. One or more data streams are transmitted over the MIMO channel to achieve good system performance.

  In the precoding technique, the base station performs linear transformation of a space domain on a signal waiting for transmission via a precoding matrix (vector) in a base station, thereby changing the channel equivalently. Precoding techniques can also significantly improve the performance of MIMO systems. In the frequency division bidirectional transmission (FDD) system, a precoding matrix is to be fed back from a user terminal (UE) to a base station. Currently, with regard to precoding processing, as a normal processing method, a base station performs precoding processing using precoding recently reported from a UE. Due to processing and feedback delays, for example, in long-time evolution (LTE, Long Term Evolution) systems, precoding typically has a delay of 5 milliseconds from the user terminal to the base station scheduler, adding the time-varying characteristics of the radio channel. Thus, in such a processing method, precoding adopted by the base station cannot be matched well with the current wireless link. On the other hand, it is indispensable to process the precoding fed back to the user terminal by the scheduler of the base station.

  A technical problem to be solved by the present invention is to provide a precoding processing method and apparatus capable of rationally predicting a transmission model to be adopted at the present time and precoding to be adopted in the transmission model for a certain UE. Is to provide.

  In order to solve the above technical problem, the present invention provides a precoding processing method. The method determines whether the effective number of effective precoding reported from the received UE is greater than or equal to a threshold a, and if so, performs step B, otherwise performs step D Step A to determine whether each received effective precoding is based on the same layer, step C if it is, step B to execute step D otherwise, and A precoding change rate rule determines if each effective precoding change is a fast change, and if so, adopts a transmit diversity transmission model for the UE, otherwise Step C adopting a MIMO transmission model for the UE and Step D adopting a MIMO transmission model for the UE. Among them, each effective precoding change is a recurrence relationship in which each effective precoding sequentially received by the base station is formed. The effective precoding is the precoding reported from the UE received by the base station in the latest time zone L. The range of the time L is 8 milliseconds to 200 milliseconds, and the threshold value a is 4 to 10.

  Further, in the step C, determining an effective precoding change rate is based on a rule for determining a vector change rate of each precoding in a layer on which each effective precoding is based. Determining a vector change rate in each precoding layer, and when each effective precoding vector change is a fast change, the number of layers reaches a preset threshold value d. Determining that the effective precoding change is a fast change. Among them, the layer is a layer based on each effective precoding, that is, a layer corresponding to a rank indicator (RI). The threshold d is an integer equal to or greater than 1 and equal to or less than the number of layers based on each effective precoding. The threshold d is preferably set to the number of layers on which each effective precoding is based. Among them, each effective precoding is a vector change in each layer, which is a recurrence relationship formed by vectors in each layer of the effective precoding sequentially received by the base station. is there.

Further, in the layer on which each effective precoding is based, a rule for determining a vector change rate of each effective precoding is:
In each layer, each effective precoding vector sequentially determines the element change speed at each same position according to the rule for determining the element change speed at the same position. If the number of positions that are fast changes is larger than the threshold value c, it is determined that the change of the vector of each precoding in the layer is a fast change, and if not, the effective values in the layer are determined. That is, it is determined that the change of the vector of the correct precoding is not a fast change. The threshold c is an integer greater than or equal to 1 and less than or equal to the number of elements in an effective precoding vector, preferably 1. The element change at the same position of each effective precoding vector is formed between elements at the same position of the vector in each layer of the effective precoding sequentially received by the base station. It is a recurrence relationship.

Further, the rule for determining the change rate of the element at the same position in each effective precoding vector in the layer includes the following steps.
Step 1: Pre-coding reception window and pre-coding trend judgment window are set in advance;
Among them, the precoding reception window receives the precoding reported from the UE, the length of the precoding reception window is equal to the time zone L, and the precoding in the precoding reception window is effective. Precoding.
The reception target of the precoding trend determination window is also the precoding reported from the UE, and is used for determining a precoding change trend. The precoding trend determination window is a subset of the precoding reception window, and the length thereof is smaller than the length of the precoding reception window.
Step 2: The element distribution type at the same position is distinguished by the precoding vector in the corresponding layer of each precoding in the precoding reception window and the precoding trend determination window.
Step 3: Based on Steps 1 and 2, the following determination is made.
If the distribution type in the precoding reception window is a static distribution or a related distribution, it is determined that the effective precoding vector is not a fast change in the element at the same position in the layer.
When the distribution type in the precoding reception window is a jumping distribution, it is further determined whether the distribution type in the precoding trend determination window is a static distribution. It is determined that the change of the element at the same position is not a fast change, and if it is not the case, it is determined that the change is a fast change.
When the distribution type in the precoding reception window is an area distribution or a scatter distribution, further determine whether the distribution type in the precoding trend determination window is a static distribution or a related distribution, and if it is a static distribution In addition, it is determined that the effective precoding vector in the layer is not a fast change of the element at the same position, and if it is a related distribution, the fast change is determined.

  Further, in the step C, when it is determined to adopt a MIMO transmission model for the UE, the base station performs MIMO transmission with precoding recently reported from the UE. If there is a layer in which each effective precoding vector change is fast according to a rule for determining a change rate of each precoding vector in a layer on which each effective precoding is based, a base station may The method further includes determining precoding to be employed in the current MIMO transmission according to a method of employing precoding by removing a corresponding vector of a fast-changing layer from the recently reported precoding.

Further, the step D includes
When the number of corresponding layers of RI recently reported from the UE is equal to or less than the number of layers currently employed, a method of performing MIMO transmission with precoding recently reported from the UE;
The most recently reported RI from the UE includes the current TTI,
When the corresponding layer number of the RI recently reported from the UE is larger than the currently employed layer number,
When the number of receiving and transmitting antennas is all 2, the precoding vector corresponding to the layer corresponding to the stream with the largest broadband CQI (CQI, Channel Quality Indicator) from the precoding recently reported from the UE The process of precoding to be adopted in one MIMO transmission,
If the number of receiving and transmitting antennas is all 4,
If the number of corresponding layers of the RI reported recently from the UE is 4, but the number of layers currently employed is 3, the precoding reported recently from the UE can be used for layer 1 or layer The precoding excluding the corresponding precoding vector of 2 is the precoding adopted in the MIMO transmission of the time,
If the number of corresponding layers of the RI reported recently from the UE is 4, but the number of layers currently employed is 2, the layer 1 or layer from the precoding recently reported from the UE The precoding vector excluding the precoding vector corresponding to 2 and the precoding vector corresponding to layer 3 or layer 4 is made the precoding adopted in the corresponding MIMO transmission,
When the number of layers corresponding to RI recently reported from the UE is 4, but the number of layers currently employed is 1, the two corresponding layers of the corresponding layer of the stream with the largest CQI are used. Making any of the coding vectors a precoding adopted in the MIMO transmission of the time,
If the number of layers corresponding to the RI reported recently from the UE is 3, but the number of layers currently employed is 2, the layer 2 or layer from the precoding recently reported from the UE Precoding excluding the vector of precoding corresponding to 3 is changed to precoding adopted in the corresponding MIMO transmission,
When the number of layers corresponding to RI recently reported from the UE is 3, but the number of layers currently employed is 1, the corresponding layer of the stream with the largest CQI corresponds to one pre-corresponding layer. A coding vector, or one of two precoding vectors, is used as the precoding adopted in the MIMO transmission of the current time,
When the number of layers supported by the recently reported RI from the UE is 2, but the number of layers currently employed is 1, the corresponding precoding of the corresponding layer of the stream with the largest CQI is used. Making the vector a precoding to be adopted in the MIMO transmission of the time,
Including a process,
The precoding to be adopted in the MIMO transmission of the time is determined by the method of adopting.

In order to solve the above technical problem, the present invention further provides a precoding processing apparatus. The apparatus determines whether the number of effective precoding reported from the UE received by the base station and the precoding receiving module that receives the precoding reported from the UE is a threshold a or more, If it is greater than or equal to the threshold a, it is further determined whether each received effective precoding is based on the same layer, and if each effective precoding is based on the same layer, each effective to determine changes in precoding are fast changed, when changing the effective precoding is fast changing, while the base station is determined to adopt transmit diversity transmission model to the UE, If the number of effective precoding reported from the UE received by the base station is not greater than or equal to the threshold a, the received effective precoding When coding may not be based on the same layer, and said a least one of the case changes in the effective precoding is not a quick change, adopting a MIMO transmission model to the UE Wherein the effective precoding is a precoding reported from the UE received by a base station in a recent time period L.

Among them, the predetermined precoding change rate rule in the step C is:
According to a rule for determining a vector change rate of each precoding in a layer based on each effective precoding determined in advance, a vector change rate in each layer of each effective precoding is determined, and When the number of layers where each effective precoding change is fast reaches a preset threshold d, it is determined that each effective precoding change is a fast change. This is the layer on which the effective precoding is based, ie the layer corresponding to the rank indicator. Preferably, the threshold d is an integer greater than or equal to 1 and less than or equal to the number of layers based on each effective precoding, and the threshold d is set to the number of layers based on each effective precoding.

  The change of vector in each layer of each effective precoding is a recurrence relationship formed by the vectors in each layer of the effective precoding sequentially received by the base station.

  The precoding processing apparatus performs MIMO transmission with the precoding recently reported from the UE by the base station, but is determined in advance, and the vector change of each precoding in a layer on which each effective precoding is based If there is a layer in which each effective precoding vector change is fast according to the rule for determining the speed, the precoding adopted by the base station corresponds to the layer that changes fast from the precoding recently reported by the UE. And a first precoding determination module for determining precoding employed in the current MIMO transmission according to the method of precoding excluding the vector to be performed.

Furthermore, the precoding processing apparatus performs MIMO transmission with the precoding recently reported from the UE when the number of layers corresponding to the RI recently reported from the UE is equal to or less than the number of layers currently employed. And how to
When the corresponding layer number of the RI recently reported from the UE is larger than the currently employed layer number,
When the number of transmitting and receiving antennas is all 2, the corresponding precoding vector of the corresponding layer of the stream with the largest broadband CQI from the precoding recently reported from the UE is adopted in the MIMO transmission of the current time The process of precoding,
If the number of receiving and transmitting antennas is all 4,
If the number of corresponding layers of the RI reported recently from the UE is 4, but the number of layers currently employed is 3, the precoding reported recently from the UE can be used for layer 1 or layer The precoding excluding the corresponding precoding vector of 2 is the precoding adopted in the MIMO transmission of the time,
If the number of corresponding layers of the RI reported recently from the UE is 4, but the number of layers currently employed is 2, the layer 1 or layer from the precoding recently reported from the UE The precoding vector excluding the precoding vector corresponding to 2 and the precoding vector corresponding to layer 3 or layer 4 is made the precoding adopted in the corresponding MIMO transmission,
When the number of layers corresponding to RI recently reported from the UE is 4, but the number of layers currently employed is 1, the two corresponding layers of the corresponding layer of the stream with the largest CQI are used. Making any of the coding vectors a precoding adopted in the MIMO transmission of the time,
If the number of layers corresponding to the RI reported recently from the UE is 3, but the number of layers currently employed is 2, the layer 2 or layer from the precoding recently reported from the UE Precoding excluding the vector of precoding corresponding to 3 is changed to precoding adopted in the corresponding MIMO transmission,
When the number of layers corresponding to RI recently reported from the UE is 3, but the number of layers currently employed is 1, the corresponding layer of the stream with the largest CQI corresponds to one pre-corresponding layer. A coding vector, or one of two precoding vectors, is used as the precoding adopted in the MIMO transmission of the current time,
When the number of layers supported by the recently reported RI from the UE is 2, but the number of layers currently employed is 1, the corresponding precoding of the corresponding layer of the stream with the largest CQI is used. Making the vector a precoding to be adopted in the MIMO transmission of the time,
Including a process,
And a second precoding determination module for determining precoding employed in the current MIMO transmission.

The beneficial effects of the present invention are:
The precoding processing method and apparatus adopted by the present invention for the existing technology is based on the fact that the base station collects, analyzes and processes precoding information reported from the UE, so that the UE can currently transmit the MIMO transmission model. Can be reasonably predicted, and the performance of the MIMO channel can be greatly improved.

It is a figure which shows the phase distribution of the element in the precoding matrix in the MIMO channel of 2 transmitting antennas and 2 receiving antennas. It is a figure which shows the phase distribution of the element in the precoding matrix in the MIMO channel of 4 transmitting antennas and 4 receiving antennas. It is a figure which shows the process of the pre-coding processing method concerning this invention. It is a figure which shows the distribution of the rank indicator and precoding in a precoding reception window. It is a figure which shows the relationship between a precoding reception window and a precoding trend determination window. It is a figure which shows the structure of the precoding processing apparatus concerning this invention.

Hereinafter, the present invention will be described in detail with reference to the drawings and specific embodiments.
First, the phase distribution of elements in the precoding matrix in the MIMO channel will be described. Mainly includes the following contents.

In the LTE system, the number of transmitting antennas is 2, the number of receiving antennas is 2, and the precoding codebook set employed in MIMO transmission in which precoding is fed back from the UE is as shown in Table 1 below. It is.

II In LTE system, the number of transmit antennas is 4, the number of receive antennas is 4, and the precoding codebook set adopted in MIMO transmission in which precoding is fed back from the UE is as shown in Table 2 below. It is.

  For the elements in each precoding matrix (vector) in Table 1 above, when considering only the phase without considering the width, it can be displayed by any one of a0, a1, a2 and a3 in the unit circle of FIG. it can. Here, in FIG. 1, the x axis is a real axis and the Y axis is an imaginary axis. a0, a1, a2, and a3 represent unit vectors having phases of 0, π / 2, π, and 3π / 2, respectively.

  For the elements in each precoding matrix (vector) in Table 2 above, when considering only the phase without considering the width, a0, b0, a1, b1, a2, b2, a3, and b3 of the unit circle in FIG. Can be displayed in any of Here, in FIG. 2, the x axis is a real axis and the Y axis is an imaginary axis. a0, b0, a1, b1, a2, b2, a3 and b3 represent unit vectors of 0, π / 4, π / 2, π3 / 4, π, π5 / 4, 3π / 2 and π7 / 4, respectively. .

  Hereinafter, with reference to FIG. 3, a description will be given of an implementation process of a suitable embodiment of the precoding processing method according to the present invention. This embodiment mainly includes the following steps.

  Step 1: The base station collects rank indicators and precoding matrix information reported from the UE.

Step 2: The base station determines whether the number of effective precodings reported from a certain UE received is greater than or equal to the threshold a, and if it is greater than or equal to the threshold a, step 3 is performed; Execute.
Among them, each effective precoding change is a recurrence relationship formed by each effective precoding sequentially received by the base station.

  In this step, the effective precoding received by the base station is precoding reported from the UE received by the base station in the latest time zone L. The precoding reported from the UE is in the effective time domain. The effective time domain is the total L millisecond time range of the current and previous L-1 milliseconds. The value of L is related to the minimum number of MIMO channel transmission antennas and reception antennas, the precoding set employed by the base station and the UE, and the precoding report period. In normal cases, the smaller the number of MIMO channel transmit and receive antennas and / or the larger the precoding set employed by the base station and the UE and / or the longer the precoding report period, the longer L Is long. This is particularly the case in a linear relationship. The range of L is 8 milliseconds to 200 milliseconds.

  Note that the value of L must ensure that the number of effective precoding reported from the UE is equal to or greater than the threshold value a (the range of a is 4 to 10). Also, from the time when the base station receives the first precoding reported from the UE to the time + L-1 time, the effective time domain increases linearly from 1 ms to L ms, Leave the effective time domain at L milliseconds. Also, after the base station deletes the effective precoding at that time, a new effective time domain is calculated from the time when the base station receives the precoding reported from the next UE. The

  Step 3: The base station determines whether each effective precoding received is based on the same number of layers, and if so, performs Step 4; otherwise, performs Step 5.

  Step 4: The base station determines whether each effective precoding change is fast according to a predetermined precoding change rate rule, and if so, sets a transmit diversity transmission model for the UE. Otherwise, adopt the MIMO transmission model for the UE.

  In this step, when it is determined that MIMO transmission is to be adopted for the UE, including precoding to be adopted in the current MIMO transmission by the following method. That is, the base station adopts the recently reported precoding from the UE and performs MIMO transmission, but the rule for determining the change rate of each precoding vector in the layer based on each effective precoding determined in advance Thus, if there is a layer where each effective precoding vector change is fast, the precoding adopted by the base station is the precoding that the UE has recently reported, excluding the corresponding vector of the layer whose change is fast. It is coding. Accordingly, in the current MIMO transmission, the number of layers employed by the base station is layer-1 corresponding to R1 reported recently from the UE. Among them, the number of layers corresponding to the RI is the number of precoding layers corresponding to the RI.

Furthermore, in this embodiment, the rules for the precoding change rate determined in advance are as follows.
According to the rule for determining the vector change of each precoding in the layer based on each effective precoding determined in advance, the vector change rate in each layer of each effective precoding is determined individually, and each effective precoding is determined. When the number of layers with fast coding vector change reaches a preset threshold value d, it is determined that each effective precoding change is fast. Among them, the layer is a layer on which each effective precoding is based, that is, a layer corresponding to a rank indicator. The threshold d is an integer equal to or greater than 1 and equal to or less than the number of layers based on each effective precoding. In this embodiment, the threshold value d is the number of layers on which each effective precoding is based.

Among them, the change of the vector in each layer for each effective precoding is a recurrence relationship in which the base station sequentially receives and each effective precoding is formed by the vector in the layer.
It goes without saying that the precoding change rate rule determined in advance in this embodiment may be another method that can be executed.

Furthermore, in this embodiment, in the layer on which each effective precoding is based, the rule for determining the vector change rate of each precoding determined in advance is:
Each effective precoding vector in each layer changes the element at each same position according to a rule that determines the change speed of the element at the same position in each layer. If the speed is determined and the number of fast-changing positions is greater than the threshold c, it is determined that the vector change of each effective precoding is fast in the layer, and if not, each effect is determined in the layer. It is determined that the change of a typical precoding vector is not fast. The threshold c is an integer equal to or greater than 1 and equal to or less than the number of elements in an effective precoding vector. In the present embodiment, the threshold c is 1.

Among them, the element change at the same position of each effective precoding vector is formed between elements at the same position of the vector in each layer of each effective precoding sequentially received by the base station. It is a recurrence relationship.
It goes without saying that the rule for determining the change rate of each precoding vector in the layer on which each effective precoding determined in advance in this embodiment is based may be another feasible method.

  Further, in the present embodiment, the rule for determining the element change rate at the same position where each effective precoding vector determined in advance in the layer includes the following steps.

Step 1: A precoding reception window and a precoding trend determination window are set in advance.
The precoding reception window is for receiving precoding information reported from the UE and RI information based on the precoding. The distribution of rank indicators and precoding in the precoding reception window is as shown in FIG. In FIG. 4, RI1 and RI2 each represent two rank indicators, PMI1-PMI5 each represent five precodings, and TTI is a transmission time interval.

  The length of the precoding reception window is the same as the time L, and the precoding in the precoding reception window is effective precoding. The length of the precoding reception window is related to the minimum number of transmission antennas and the number of reception antennas of the MIMO channel, the precoding set employed by the base station and the UE, and the precoding report period. In the normal case, the larger the minimum number of transmit and receive antennas in the MIMO channel and / or the larger the precoding set employed in the base station and the UE and / or the longer the precoding report period, the longer the precoding. The reception window is also long. In particular, it has a linear relationship. It should also be noted that the precoding reception window must ensure that the number of received precodings is greater than the threshold value a.

  The reception target of the precoding trend determination window is also the precoding information reported from the UE and the RI information based on the precoding. The precoding trend determination window is a subset of the precoding reception window, and is used to determine the precoding change trend, and its length is smaller than the length of the precoding reception window. The length is 1/2 or 1/3 (rounded up). Let L 'be the length of the precoding trend judgment window. The range of L ′ is 4 milliseconds to 100 milliseconds. In addition, it is necessary to ensure that the number of precodings received by the precoding trend determination window is equal to or greater than the threshold value E. The range of threshold E is 2-5. The precoding trend determination window is in a time range that is L-1 milliseconds before the current TTI point and the total L milliseconds before the current TTI point. FIG. 5 shows the relationship between the precoding reception window and the precoding trend determination window.

  Step 2: The element distribution type at the same position of the precoding vector in the layer for each precoding in the precoding reception window and the precoding trend determination window is determined. Among them, the distribution in the precoding reception window is as follows.

  Distribution 1: Static distribution in which the vector in the corresponding layer of each precoding in the precoding reception window does not change the phase at the same position. For example, in the case of MIMO channels with 2 transmit antennas and 2 receive antennas, all are distributed in the set {a0} of FIG. 1, and in the case of MIMO channels of 4 transmit antennas and 4 receive antennas, in the set {b0} of FIG. Distributed.

  Distribution 2: A related distribution in which the phase difference of the elements at the same position of the vector of each precoding in the corresponding layer in the precoding reception window does not exceed π / 2. For example, in the case of a MIMO channel with two transmit antennas and two receive antennas, it is distributed in the set {a0, a1} in FIG. 1, and in the case of a MIMO channel with four transmit antennas and four receive antennas, the set {a0, b0, a1}.

  Distribution 3: A jumping distribution in which the vector in the corresponding layer of each precoding in the precoding reception window has a phase difference of π at the same position. For example, in the case of a MIMO channel with two transmitting antennas and two receiving antennas, it is distributed in the set {a0, a2} in FIG. 1, and in the case of a MIMO channel with four transmitting antennas and four receiving antennas, the set {b0, b2}.

  Distribution 4: An area distribution in which the vector in the corresponding layer of each precoding in the precoding reception window does not exceed the element phase difference at the same position and is distributed only in one of the unit circles. . For example, in the case of a MIMO channel with 2 transmit antennas and 2 receive antennas, it is distributed in the set {a0, a1, a2} of FIG. 1, and in the case of a MIMO channel of 4 transmit antennas and 4 receive antennas, the set of FIG. b0, a1, b1, a2, b2}.

  Distribution 5: A scattering distribution in which a vector in each layer of each precoding in the precoding reception window is distributed over the entire phase unit circle of the element at the same position. For example, in the case of a MIMO channel with 2 transmit antennas and 2 receive antennas, it is distributed in the set {a0, a1, a2, a3} in FIG. 1, and in the case of a MIMO channel with 4 transmit antennas and 4 receive antennas, FIG. Distributed in the set {b0, a1, b1, a2, b2, a3, b3}.

  Among them, the precoding trend determination window is used only in the case of the jumping distribution, area distribution, or scattering distribution in the precoding reception window. Distribution types in the precoding trend determination window include distribution 1, distribution 2, and other distributions. In the precoding trend determination window, the definitions of distribution one, that is, static distribution, and distribution two, that is, related distribution, are the same as those in the precoding reception window. The other distribution in the precoding trend determination window is a distribution other than the static distribution and the related distribution.

  In the LTE system, there are only two values for precoding in two layers, and the distribution type is divided into only a static distribution and a jumping distribution.

Step 3: Based on steps 1 and 2, make the following determinations.
When the distribution type in the precoding reception window is distribution 1 or distribution 2, it is determined that each effective precoding vector is not a change in which the element change at the same position is a fast change in the layer.

  If the distribution type in the precoding reception window is distribution 3, further determine whether the distribution type in the precoding trend determination window is the same as the distribution, and if so, each effective precoding vector of the layer is determined. It is determined that the change of the element at the same position is not a fast change, and otherwise, it is determined that the change is fast.

  If the distribution type in the precoding reception window is distribution four or distribution five, then it is determined whether the distribution type in the precoding trend determination window is distribution one or distribution two. It is determined that the change of the element at the same position of each effective precoding vector in the layer is not a fast change, and if the distribution is two, the change is determined to be a fast change.

  Note that when the related distribution types in the precoding reception window are different, the lengths of the precoding trend determination windows are also different. Among them, when the distribution type in the precoding reception window is a jumping distribution, the precoding trend determination window is 1/3 to 1/2 (rounded up) of the length of the precoding reception window. When the distribution type in the precoding reception window is area distribution, the length of the precoding trend determination window is min {1/3 to 1/2 of the length of the precoding reception window (rounded up), and the length of the precoding reception window -DeltaN1}, where the value of deltaN1 is equal to or greater than 3 and less than the length of the precoding reception window for a MIMMO channel with 2 transmit antennas and 2 receive antennas, 4 transmit antennas and 4 receive In the case of the antenna MIMMO channel, deltaN1 is 5 or more and smaller than the length of the precoding reception window. When the distribution type in the precoding reception window is a scatter distribution, the length of the precoding trend determination window is min {1/3 to 1/2 of the precoding reception window length (rounded up), Length−deltaN2}, where the value of deltaN2 is greater than or equal to 4 and less than the length of the precoding receive window for a 2 transmit antenna and 2 receive antenna MIMMO channel, 4 transmit antennas and 4 In the case of the MIMMO channel of the receiving antenna, deltaN2 is 6 or more and smaller than the length of the precoding reception window.

  In the present invention, the method for determining the element change rate at the same position of each effective precoding vector in the layer determined in advance may be another method that can be executed. In particular, it can be determined by, for example, a dispersion method.

Step 5: Adopt the MIMO transmission model and determine the precoding to be used in the current MIMO transmission.
In this step, precoding to be adopted in the MIMO transmission of this time is determined mainly by the following method.

  I) When the number of layers corresponding to the RI reported recently from the UE is less than or equal to the number of layers currently employed, MIMO transmission is performed with the precoding reported recently from the UE.

  II) When the number of layers corresponding to the RI recently reported from the UE is larger than the number of layers currently employed, the following processing process is performed.

  i) When the number of receiving and transmitting antennas is all 2, the precoding corresponding to the layer corresponding to the stream with the largest channel quality indication (CQI, Channel Quality Indicator) from the precoding recently reported from the UE Are precoded for use in the MIMO transmission.

ii) When the number of receiving and transmitting antennas is all 4,
(1) When the number of corresponding layers of the RI reported recently from the UE is 4 and the number of layers currently employed is 3, the precoding reported recently from the UE Alternatively, the precoding excluding the precoding vector corresponding to the layer 2 is set as the precoding used in the corresponding MIMO transmission.

  (2) When the number of layers corresponding to the RI reported recently from the UE is 4 and the currently employed layer is 2, the layer 1 of the precoding recently reported from the UE Alternatively, the precoding vector excluding the precoding vector corresponding to the layer 2 and the precoding vector corresponding to the layer 3 or the layer 4 is used as the precoding adopted in the MIMO transmission.

  (3) If the number of layers corresponding to RI recently reported from the UE is 4 and the number of layers currently employed is 1, the stream corresponding to the stream with the largest CQI corresponds to 2 Any one of the two precoding vectors is used as the precoding employed in the MIMO transmission.

  (4) When the number of layers corresponding to the RI reported recently from the UE is 3, and the number of layers currently employed is 2, the layer 2 or The precoding excluding the precoding vector corresponding to layer 3 is used as the precoding adopted in the MIMO transmission of the current time.

  (5) When the number of layers corresponding to RI recently reported from the UE is 3 and the number of layers currently employed is 1, the corresponding layer of the stream with the largest CQI Either one of the two precoding vectors or the two precoding vectors is used as the precoding employed in the current MIMO transmission.

  (6) When the number of layers corresponding to the RI recently reported from the UE is 2 and the number of layers currently employed is 1, the corresponding pre-layer of the corresponding layer of the stream with the largest CQI is used. The coding vector is set to precoding adopted in the corresponding MIMO transmission.

  Note that the precoding processing method of the present invention is applied to MIMO transmission models other than open-loop MIMO, such as closed-loop MIMO, multi-user MIMO, and closed-loop MIMO with a rank indicator of 1. Note that the RI recently reported from the UE currently includes the TTQ.

  The above is a preferred embodiment of the precoding processing method of the present invention, and two specific embodiments according to the present invention will be described below.

Embodiment 1 In this embodiment, for a MIMO channel in which the transmission antenna _NT is 2 and the reception antenna N _R is 2, the UE transmission model is closed-loop MIMO, and precoding reception for the UE is performed. The window length L is set to 20 milliseconds, the threshold value a is 4, the threshold value c is 1, and the threshold value d is 2.

であり、（１,２）はUEから報告されたプリコーディングが

であることを表す。 At some point, the precoding in the precoding reception window of the UE is [[1, 0), (1, 0), (1, 2), (1, 0), (1, 2), (1 , 0)], in which the second element in parentheses “()” representing precoding is a precoding matrix index (PMI, Precoding Matrix Index) reported from the UE, and represents parentheses representing precoding. The first element in “()” is the number of layers corresponding to the rank indicator (RI, Rank Indicator) based on the PMI reported from the UE. For the base station, RI corresponds to the number of layers, that is, the number of layers = RI + 1. As can be seen from Table 1, (1,0) is the precoding reported from the UE.

(1,2) is the precoding reported from the UE.

It represents that.

  Step 1: Determine that the precoding in the precoding reception window is full, i.e., if the number of effective precoding reported from the UE received by the base station is greater than the threshold a, Proceed to step.

  Step 2: If it is determined that each precoding in the precoding reception window is based on the same number of layers (all are one layer), proceed to the next step.

  Step 3: Each precoding in the precoding reception window sequentially determines the rate of change in each layer and includes the following steps.

First, each precoding in the precoding reception window determines the rate of change in layer 1. Among them, the vector in layer 1 of each precoding in the precoding reception window sequentially determines the element change speed at each same position,
Step 3.1: It is determined that the distribution type is a static distribution when the element distribution at the first position of the vector in layer 1 in the precoding reception window is in the set {a0} in FIG. . Thus, it can be determined that the vector at layer 1 of each precoding in the precoding reception window is a slow change of the element at the first position;
Step 3.2: Each precoding in the precoding reception window is determined that the element distribution at the second position of the vector at layer 1 is in the set {a0, a1} in FIG. To do. Thus, the vector at layer 1 of each precoding in the precoding reception window includes being able to determine that the element at the second position is a slow change.

  Therefore, each precoding in the precoding reception window is a slow change at layer 1.

  Step 4: The number of layers based on each precoding in the precoding reception window is all layer 1, but from step 3, it is clear that each precoding in the precoding reception window is a slow change in layer 1 Therefore, MIMO transmission is performed using precoding recently reported from the UE. Here, the process of determining the UE transmission model and the precoding employed in the transmission model according to the present embodiment ends.

Embodiment 2 In this embodiment, for a MIMO channel in which the transmission antenna _NT is 4 and the reception antenna N _R is 4, the UE transmission model is closed-loop MIMO, and the precoding reception window for the UE The threshold L is 24 milliseconds, the threshold a is 5, the threshold c is 1, and the threshold d is 4.

であることを表す。該UEが当該時点に用いるレイヤー数を1にし、当該時点にUEのストリーム1の報告ブロードバンドCQIを5として、ストリーム2の報告ブロードバンドCQ1を6とする。 At some point, the precoding in the precoding reception window of the UE is [(1, 0), (1, 1), (1, 2), (1, 2), (1, 3), (2 , 0), (2, 1), (2, 0)]. As shown in Table D, (2,0) is the precoding reported from the UE.

It represents that. The number of layers used by the UE at that time is set to 1, the reporting broadband CQI of the stream 1 of the UE is set to 5 at that time, and the reporting broadband CQ1 of the stream 2 is set to 6.

  Step 1: It is determined that precoding in the precoding reception window is already full, and the process proceeds to the next step.

  Step 2: It is determined that each precoding in the precoding reception window is not based on the same number of layers, and the following processing process is performed for the difference in the number of layers based on precoding in the precoding reception window.

  Step 2.1: Hold all precoding matrices reported by the recently reported RI in the precoding reception window and delete other precoding matrices in the precoding reception window. That is, the precoding in the precoding reception window of the UE at this time is [(2, 0), (2, 1), (2, 0)].

を該時点のプリコーディングとしてMIMO伝送する。その中、該時点にプリコーディングが依拠するレイヤー数が、即ち基地局が受信した該UEから最近に報告されたRIが対応するレイヤー数である。ここで、本実施例による前記UEの伝送モデルおよび該伝送モデルで採用されるプリコーディングを確定するプロセスが終了する。 Step 2.2: The number of layers based on precoding at the time of the UE is larger than the number of layers used at the time, and the number of layers based on precoding at the time is 2, and the number of layers used at the time is Since the broadband CQ1 at which the UE reports stream 1 is 5 and the reporting broadband CQ1 of stream 2 is 6 at that time, the corresponding layer 2 of stream 2 corresponds to the precoding vector.

Are transmitted as MIMO as precoding at that time. Among them, the number of layers on which precoding relies at that time is the number of layers to which the RI recently reported from the UE received by the base station corresponds. Here, the process of determining the UE transmission model and the precoding employed in the transmission model according to the present embodiment ends.

  The present invention further provides a precoding processing apparatus. Hereinafter, a precoding processing apparatus according to the present invention including a precoding receiving module and a transmission model selection module will be described with reference to FIG.

  FIG. 6 is a diagram showing the structure of a precoding processing apparatus according to the present invention. As shown in FIG. 6, the precoding processing apparatus of the present invention includes a precoding receiving module and a transmission model selection module.

  Among them, the precoding receiving module receives the precoding and rank indicator reported from the UE. The transmission model selection module determines whether the number of effective precodings reported from the UE received by the base station is greater than or equal to a threshold value a. If the effective precoding is based on the same number of layers, and if each effective precoding is based on the same number of layers, it is further determined whether each effective precoding change is a fast change. Determine, if the effective precoding change is a fast change, the base station adopts transmit diversity for the UE, otherwise decides to adopt the MIMO transmission model for the UE To do. Among them, the effective precoding is the precoding reported from the UE received by the base station in the recent time zone L.

  Further, the transmission model selection module is used to determine a transmission model to be adopted for a UE having a base station by the following method.

A. Determine whether the number of effective precodings reported from the UE received by the base station is greater than or equal to the threshold a, and if so, perform step B, otherwise execute step D.
Among them, the effective precoding received by the base station is that the precoding reported from the UE is in an effective time domain. The effective time domain is within a time range of total L milliseconds of the current time point and L-1 milliseconds before the current time point. Here, the range of L is 8 milliseconds to 200 milliseconds, and the value of L must ensure that the number of effective precoding reported from the UE is larger than the threshold a. The range of the threshold value a is 4-10.

  B. Determine whether each received effective precoding is based on the same number of layers. If yes, perform step C, otherwise execute step D.

C. Determine whether each effective precoding change is a fast change according to a predetermined precoding change rate rule, and if so, adopt a transmit diversity transmission model for the UE. Otherwise, adopt the MIMO transmission model for the UE.
Each effective precoding change is a recurrence relationship formed by each effective precoding sequentially received by the base station.

  D, adopt MIMO transmission model for the UE.

  In the present embodiment, the rule for the precoding change rate determined in advance in step C is the rule for determining the vector change rate for each precoding in a layer that is determined in advance and based on each effective precoding. By determining the vector change rate in each layer for each effective precoding, and when the number of layers for each effective precoding vector change reaches a preset threshold d, Determining that the effective precoding change is a fast change. Among them, the layer is a layer based on each effective precoding, that is, a layer corresponding to a rank indicator (RI). The threshold d is an integer equal to or greater than 1 and equal to or less than the number of layers based on each effective precoding. For example, the threshold value d can be set to the number of layers based on each effective precoding.

  Among these, each effective precoding is a vector change in each layer, which is a recurrence relationship formed by vectors in each layer of the effective precoding sequentially received by the base station. .

  The precoding processing apparatus further includes a first precoding determination module and a second precoding determination module.

  Among them, when the first precoding determination module determines in step C in the transmission model selection scheme adopted in the transmission model selection module that the UE adopts the MIMO transmission model in the step The first precoding determination module determines the precoding to be used in the MIMO transmission of the current time according to the following scheme.

  The base station performs MIMO transmission with the recently reported precoding from the UE, but according to the rules for determining the vector change rate of each precoding at the layer on which each effective precoding determined in advance is based, When it is determined that there is a layer with a fast vector change of effective precoding, the precoding adopted by the base station adopts a precoding in which the vector corresponding to the fast change layer is deleted from the precoding reported by the UE. To do.

  The second precoding determination module determines the precoding to be used in the MIMO transmission in the following manner in step D in the transmission model selection method adopted in the transmission model selection module.

  I) When the number of layers corresponding to the RI reported recently from the UE is less than or equal to the number of layers currently employed, MIMO transmission is performed with the precoding recently reported from the UE.

  II) When the number of layers corresponding to the RI recently reported from the UE is larger than the number of layers currently employed, the following processing process is performed.

  i) When the number of receiving and transmitting antennas is all 2, the precoding corresponding to the layer corresponding to the stream with the largest channel quality indicator (CQI, Channel Quality Indicator) from the precoding recently reported from the UE Are precoded for the MIMO transmission.

ii) When the number of receiving and transmitting antennas is all 4,
(1) When the number of corresponding layers of the RI reported recently from the UE is 4 and the number of layers currently employed is 3, the precoding reported recently from the UE Alternatively, precoding excluding the corresponding precoding vector of layer 2 is used as precoding employed in the current MIMO transmission.

  (2) If the number of layers supported by the RI reported recently from the UE is 4, and the currently adopted layer is 2, the layer 1 or layer from the precoding recently reported from the UE The precoding vector excluding the precoding vector corresponding to 2 and excluding the precoding vector corresponding to layer 3 or layer 4 is used as the precoding adopted in the current MIMO transmission.

  (3) If the number of layers corresponding to RI recently reported from the UE is 4 and the number of layers currently employed is 1, the corresponding layer of the stream with the largest CQI Any one of the two precoding vectors is used as the precoding employed in the MIMO transmission.

  (4) When the number of layers corresponding to the RI reported recently from the UE is 3, and the number of layers currently employed is 2, the layer 2 or The precoding excluding the precoding vector corresponding to layer 3 is used as the precoding adopted in the MIMO transmission of the current time.

  (5) When the number of layers corresponding to RI recently reported from the UE is 3 and the number of layers currently employed is 1, the corresponding layer of the stream with the largest CQI Either one of the two precoding vectors or the two precoding vectors is used as the precoding employed in the current MIMO transmission.

  (6) When the number of layers corresponding to the RI recently reported from the UE is 2 and the number of layers currently employed is 1, the corresponding pre-layer of the corresponding layer of the stream with the largest CQI is used. The coding vector is set to precoding adopted in the corresponding MIMO transmission.

  In the above description, the precoding and the precoding matrix are the same concept. When the precoding matrix has only one column, the precoding matrix is a precoding vector.

  The above are only specific examples for explaining the object, technical idea and beneficial effects of the present invention in more detail, and do not limit the present invention. A person skilled in the art can make any change or modification without departing from the spirit and scope of the present invention. Thus, if these changes and modifications in the present invention belong to the technical idea described in the claims of the present invention and the equivalent technical scope thereof, these changes and modifications are also included in the protection scope of the present invention.

Claims (10)

The base station determines whether the number of effective precodings reported from the received UE is greater than or equal to a threshold a, and if so, performs step B; otherwise, performs step A and ,
Determining whether each received effective precoding is based on the same layer, and if so, performing step C, otherwise performing step D; and
Determine if each effective precoding change is a fast change and if so, adopt a transmit diversity transmission model for the UE and terminate the process, otherwise for the UE Adopting MIMO transmission model and ending the process step C,
Adopting a MIMO transmission model for the UE, and
The effective precoding is a precoding reported from the UE received by a base station in a recent time zone L.
And a precoding processing method.   2. The precoding processing method according to claim 1, wherein the value of the time L is 8 milliseconds to 200 milliseconds, and the value of the threshold value a is 4 to 10. In step C, determining an effective precoding change rate is:
In the layer on which each effective precoding is based, a vector change rate in each effective precoding layer is determined according to a rule for determining a vector change rate in each precoding, and each effective precoding is determined. When the number of layers whose fast precoding vector change is a fast change reaches a preset threshold d (d is an integer greater than or equal to 1 and less than or equal to the number of layers based on each effective precoding), 2. The precoding processing method according to claim 1, comprising determining that each effective precoding change is a fast change. In the layer on which each effective precoding is based, the rule for determining the vector change rate of each effective precoding is:
In each layer, each effective precoding vector sequentially determines the element change speed at each same position according to the rule for determining the element change speed at the same position. If the number of positions that are fast changes is greater than a threshold c (c is an integer that is greater than or equal to 1 and less than or equal to the number of layers on which each effective precoding is based), the vector change of each precoding at that layer 4. Precoding according to claim 3, characterized in that is determined to be a fast change, otherwise it is determined that the change of each effective precoding vector in the layer is not a fast change. Processing method. In the layer, the rule for determining the change speed of the element at the same position of each effective precoding vector is:
Step 1 for pre-installing a precoding reception window and a precoding trend determination window;
Step 2 in which the precoding vector in the corresponding layer of each precoding in the precoding reception window and the precoding trend determination window classifies element distribution types at the same position;
Based on steps 1 and 2,
If the distribution type in the precoding reception window is a static distribution or a related distribution, determining that each effective precoding vector is not a fast change in the element at the same position in the layer. ,
When the distribution type in the precoding reception window is a jumping distribution, it is further determined whether the distribution type in the precoding trend determination window is a static distribution. Determining that the precoding vector is not a fast change of the element at the same position, otherwise it is a fast change;
When the distribution type in the precoding reception window is an area distribution or a scatter distribution, further determine whether the distribution type in the precoding trend determination window is a static distribution or a related distribution, and if it is a static distribution Determining that each effective precoding vector in the layer is not a fast change of the element at the same position, and if it is a related distribution, determining that it is a fast change. 5. The precoding processing method according to claim 4, comprising 3. In step C,
If you decide to adopt the MIMO transmission model for the UE,
If the base station performs MIMO transmission with the recently reported precoding from the UE, but there is a layer where each effective precoding vector change is fast, the base station may By adopting precoding by removing the corresponding vector of the fast-changing layer from coding,
6. The precoding processing method according to claim 1, further comprising: determining precoding employed in the MIMO transmission of the time. In step D,
When the number of corresponding layers of RI recently reported from the UE is equal to or less than the number of layers currently employed, a method of performing MIMO transmission with precoding recently reported from the UE;
When the corresponding layer number of the RI recently reported from the UE is larger than the currently employed layer number,
When the number of transmitting and receiving antennas is all 2, the corresponding precoding vector of the corresponding layer of the stream with the largest broadband CQI from the precoding recently reported from the UE is adopted in the MIMO transmission of the current time The process of precoding,
If the number of receiving and transmitting antennas is all 4,
If the number of corresponding layers of the RI reported recently from the UE is 4, but the number of layers currently employed is 3, the precoding reported recently from the UE can be used for layer 1 or layer The precoding excluding the corresponding precoding vector of 2 is the precoding adopted in the MIMO transmission of the time,
If the number of corresponding layers of the RI reported recently from the UE is 4, but the number of layers currently employed is 2, the layer 1 or layer from the precoding recently reported from the UE The precoding vector excluding the precoding vector corresponding to 2 and the precoding vector corresponding to layer 3 or layer 4 is made the precoding adopted in the corresponding MIMO transmission,
When the number of layers corresponding to RI recently reported from the UE is 4, but the number of layers currently employed is 1, the two corresponding layers of the corresponding layer of the stream with the largest CQI are used. Making any of the coding vectors a precoding adopted in the MIMO transmission of the time,
If the number of layers corresponding to the RI reported recently from the UE is 3, but the number of layers currently employed is 2, the layer 2 or layer from the precoding recently reported from the UE Precoding excluding the vector of precoding corresponding to 3 is changed to precoding adopted in the corresponding MIMO transmission,
When the number of layers corresponding to RI recently reported from the UE is 3, but the number of layers currently employed is 1, the corresponding layer of the stream with the largest CQI corresponds to one pre-corresponding layer. A coding vector, or one of two precoding vectors, is used as the precoding adopted in the MIMO transmission of the current time,
When the number of layers supported by the recently reported RI from the UE is 2, but the number of layers currently employed is 1, the corresponding precoding of the corresponding layer of the stream with the largest CQI is used. Making the vector a precoding to be adopted in the MIMO transmission of the time,
Including a process,
6. The precoding processing method according to any one of claims 1 to 5, further comprising: determining a precoding employed in the MIMO transmission of the current time by a method employing the above. The precoding receiving module for receiving precoding reported from a UE;
It is determined whether the number of effective precodings reported from the UE received by the base station is greater than or equal to a threshold value a. If the number is equal to or greater than the threshold value a, each received effective precoding is the same layer. If each effective precoding is based on the same layer, it is further determined whether each effective precoding change is a fast change, and effective precoding change. Is a fast change, the base station determines to adopt a transmit diversity transmission model for the UE, while the number of effective precoding reported from the UE received by the base station is a threshold. If not greater than a, each received effective precoding is not based on the same layer, and each effective precoding change If it is at least one of if not the fast changes, and a said transmission model selection module for determining to adopt MIMO transmission model to the UE,
Among them, the effective precoding is a precoding reported from the UE received by a base station in a recent time zone L.   When the base station performs MIMO transmission with the precoding recently reported from the UE, but there is a layer in which each effective precoding vector change is fast, the precoding adopted by the base station is the latest from the UE. A first precoding determination module for determining the precoding employed in the MIMO transmission of the current time according to the method of precoding by removing the corresponding vector of the fast-changing layer from the precoding reported in 9. The precoding processing apparatus according to claim 8, wherein When the number of corresponding layers of RI recently reported from the UE is equal to or less than the number of layers currently employed, a method of performing MIMO transmission with precoding recently reported from the UE;
When the corresponding layer number of the RI recently reported from the UE is larger than the currently employed layer number,
When the number of transmitting and receiving antennas is all 2, the corresponding precoding vector of the corresponding layer of the stream with the largest broadband CQI from the precoding recently reported from the UE is adopted in the MIMO transmission of the current time The process of precoding,
If the number of receiving and transmitting antennas is all 4,
If the number of corresponding layers of the RI reported recently from the UE is 4, but the number of layers currently employed is 3, the precoding reported recently from the UE can be used for layer 1 or layer The precoding excluding the corresponding precoding vector of 2 is the precoding adopted in the MIMO transmission of the time,
If the number of corresponding layers of the RI reported recently from the UE is 4, but the number of layers currently employed is 2, the layer 1 or layer from the precoding recently reported from the UE The precoding vector excluding the precoding vector corresponding to 2 and the precoding vector corresponding to layer 3 or layer 4 is made the precoding adopted in the corresponding MIMO transmission,
When the number of layers corresponding to RI recently reported from the UE is 4, but the number of layers currently employed is 1, the two corresponding layers of the corresponding layer of the stream with the largest CQI are used. Making any of the coding vectors a precoding adopted in the MIMO transmission of the time,
If the number of layers corresponding to the RI reported recently from the UE is 3, but the number of layers currently employed is 2, the layer 2 or layer from the precoding recently reported from the UE Precoding excluding the vector of precoding corresponding to 3 is changed to precoding adopted in the corresponding MIMO transmission,
When the number of layers corresponding to RI recently reported from the UE is 3, but the number of layers currently employed is 1, the corresponding layer of the stream with the largest CQI corresponds to one pre-corresponding layer. A coding vector, or one of two precoding vectors, is used as the precoding adopted in the MIMO transmission of the current time,
When the number of layers supported by the recently reported RI from the UE is 2, but the number of layers currently employed is 1, the corresponding precoding of the corresponding layer of the stream with the largest CQI is used. Making the vector a precoding to be adopted in the MIMO transmission of the time,
Including a process,
10. The precoding processing apparatus according to claim 8 or 9, further comprising a second precoding determination module that determines precoding to be employed in the current MIMO transmission by a method employing

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